Single-use syringe

ABSTRACT

A single use syringe ( 10 ) includes a needle ( 18 ), barrel ( 16 ), plunger assembly ( 20 ) and shield ( 12 ). The barrel ( 16 ) bears a locking member ( 26 ) which encircles the front end of the barrel ( 16 ) and is carried forward by the barrel ( 16 ) to a position where it engages the shield ( 12 ) and is retained by the shield ( 12 ) such that the locking member ( 26 ) is separated from the barrel ( 16 ) as the barrel ( 16 ) is withdrawn rearwardly after use. The locking member ( 26 ) is resilient and, after it is removed from the barrel ( 16 ), assumes a configuration which prevents subsequent forward movement of the barrel ( 16 ) within the shield ( 12 ). The barrel includes a frangible seal ( 30 ) which is broken by rearward movement of needle mount ( 32 ). The shield ( 12 ) includes a shield extender ( 14 ) for controlling the depth of penetration of the needle. The syringe can also be used to inject medicament into a IV bag via a male port as shown in FIG.  7.

RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No.: 10/206,868, filed Jul. 26, 2002, which is a continuation under35 U.S.C. 1.111 (a) of International Application No. PCT/AU00/01027filed Aug. 30, 2000 and published in English as WO 01/54758 A1 on Aug.2, 2001, which claimed priority from Australian Applications PQ 5249filed Jan. 27, 2000, and PQ 8484 filed Jul. 3, 2000, which applicationsand publication are incorporated herein by reference.

FIELD OF INVENTION

[0002] The present invention relates to single-use syringes.

BACKGROUND OF THE INVENTION

[0003] In recent times there has been a proliferation of single-usesyringe designs which incorporate shields that can be moved to a forwardposition to shield the needle after use. In most instances, the shieldis locked in the forward position after use to prevent multiple uses ofthe syringe and/or to prevent inadvertent needle-stick injury.

[0004] Examples of syringe designs incorporating shields can be found inU.S. Pat. No. 5,584,818 to Morrison, U.S. Pat. No. 5,492,536 to Mascia,U.S. Pat. No. 5,527,294 to Weatherford, U.S. Pat. No. 5,591,138 toVaillancourt, U.S. Pat. No. 6,099,504 to Gross, U.S. Pat. No. 4,820,275to Haber, U.S. Pat. No. 5,269,761 to Stehrenberger, U.S. Pat. No.5,562,626 to Sanpietro, U.S. Pat. No. 4,863,434 to Bayless, U.S. Pat.No. 4,985,021 to Straw, U.S. Pat. No. 5,057,079 to Tiemann, U.S. Pat.No. 5,057,086 to Dillard, U.S. Pat. No. 5,092,851 to Ragner, U.S. Pat.No. 5,201,720 to Borgia, U.S. Pat. No. 5,215,534 to De Harde, U.S. Pat.No. 5,215,535 to Gettig, U.S. Pat. No. 5,222,945 to Basnight, U.S. Pat.No. 5,290,256 to Weatherford, U.S. Pat. No. 5,312,372 to De Harde, andU.S. Pat. No. 5,360,408 to Vaillancourt.

[0005] Most of these shielded-syringe designs are provided to the userwith the shield in the retracted position and thus some triggering ormanual manipulation of the shield is required to release the shield tothe forward position after use. In many designs, the movement of theshield to the forward position after use is assisted by a spring.

[0006] Only a few of these known designs are provided to the user withthe shield initially in the forward position. In these cases, it isnecessary for the user to manipulate some form of release mechanism toenable the shield to be moved to the rearward position to expose theneedle for use, and after use it is again necessary to manipulate someform of release mechanism to release the shield to the forward position.Again, many of these designs incorporate a spring which biases theshield to the forward position.

SUMMARY OF INVENTION

[0007] According to one aspect the invention resides in a single-usesyringe which is provided to the user with the shield in a forwardposition, yet requires no manual manipulation of release mechanisms orthe like to release the shield to the rearward position for use, norfurther manual manipulation to release and lock the shield in theforward position after use.

[0008] The above ergonomic advantages are achieved by a single-usesyringe as defined in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention will now be described with reference to an examplefor illustrative purposes and wherein:—

[0010] FIGS. 1 to 6 are a series of sequential longitudinal sectionedviews of a single-use syringe demonstrating operation of the single-usesyringe; and

[0011]FIG. 7 shows the single-use syringe engaging the male port of anIV fluid bag.

DETAILED DESCRIPTION

[0012] Referring firstly to FIG. 1, there is illustrated a pre-filledsingle-use syringe 10 including a shield 12 having a shield extender 14,a barrel 16 mounted for reciprocation within the shield 12 and having aneedle 18 at its forward end, and a plunger assembly 20 mounted forreciprocation within the barrel 16.

[0013] The shield 12 is generally cylindrical in shape and includes agenerally cylindrical shield extender 14 at its forward end. The shieldextender 14 can be selectively extended to control the depth ofpenetration of the needle during use as will be described in more detaillater. Conventional finger receiving portions 22 are defined towards therear end of the shield 12, the finger receiving portions 22 adapted toreceive a user's fingers in the conventional manner during use. Theforward end of the shield includes a circular slot 24 which engages aretains a locking member 26 during use as will be described later. Therearward end of the shield includes a rear collar flange 28 which limitsthe barrel's 16 rearward travel within the shield 12.

[0014] The barrel 16 is pre-filled with medicament and is sealed at itsrearward end by the plunger assembly 20 and at the forward end by afrangible seal 30 which can be broken by the needle mount 32 prior touse as will be discussed later. The needle 18 extends forwardly from theneedle mount 32 which is itself located immediately forward of thefrangible seal 30. The barrel 16 bears a generally cylindricalbifurcated locking member 26 about its forward end which is adapted toengage and be retained by the circular slot 24 in the shield 12 as willbe described in greater detail later.

[0015] The plunger assembly 20 is conventional in construction andincludes a piston 34 at its forward end which sealingly engages theinternal bore of the barrel 16.

[0016] The plunger assembly 20 also defines a conventional thumbengaging portion 36 at its rearward end.

[0017] Referring firstly to FIG. 1 there is illustrated a pre-filledsingle-use syringe in the form in which it would be supplied to a user.Normally, the pre-filled single-use syringe 10 would be individuallypackaged and supplied in a sterile plastic package which is notillustrated. Both the packaging and syringe itself would identify themedicament and volume of medicament present in the barrel of thesyringe.

[0018] As mentioned above, the medicament is sealed within the barrel 16by the piston 34 of the plunger assembly 20 at the rearward end of thebarrel 16 and by a frangible seal 30 at the forward end of the barrel16.

[0019] The first step in the use of the syringe is the breaking of thefrangible seal 30 and this is best understood with comparative referenceto FIGS. 1 and 2.

[0020] Shield extender 14 is mounted via a coarse screw thread on theforward end of shield 12 such that rotation of shield extender 14relative to shield 12 causes the shield extender to reciprocate in theforward or aft direction relative to shield 12.

[0021] As can be seen with reference to FIG. 1, the syringe is providedwith the shield extender 14 in a slightly forward position, i.e. theshield extender 14 extends slightly forward beyond the forward-mostextent of the shield 12.

[0022] A cap 38 is provided, and the cap 38 has an outer skirt which isfrictionally seated on the shield extender 14 as shown. The shieldextender 14 also has a small outwardly extending shoulder which isengaged by the outer skirt and prevents rearward movement of the cap 38relative to the shield extender 14. The cap 38 also encloses the needle18 with a rearwardly extending inner skirt which seats on the taperedforward end of the needle mount 32 as shown.

[0023] With reference now to FIG. 2, the cap 38 and shield extender 14have been rotated relative to shield 12 such that the shield extender 14and cap have moved in unison rearwardly relative to shield 12 until therear end of the shield extender 14 has abutted a small outwardlyextending shoulder formed on the shield 12 which prevents furtherrearward movement of the shield extender 14 relative to the shield 12.Simultaneously, the needle mount 12 has been driven rearwardly by theinner skirt of the cap 38 such the frangible seal 30 has been broken andthe needle 18 is thus now in fluid communication with the interior ofthe barrel 16. The frangible seal 30 is designed to have a portion ofits circumference form a “live” or integral hinge about which theremainder of the frangible seal 30 pivots. A frangible seal and livehinge per se is known from PCT/AU99/00422.

[0024] It will be noted that the needle mount 32 is non-conventional inconstruction in that it is cylindrical and fully contained within theseal-containing bore of the spigot-shaped nose of the barrel 16. Incontrast, conventional needle mounts include a rearwardly projectingskirt which surrounds the exterior of the spigot-shaped nose of thebarrel 16. It is for this reason that the syringe disclosed inPCT/AU99/00422 utilised a cylindrical tube 21 intermediate theconventional needle mount 7 and frangible seal 9 for the purpose ofbreaking the frangible seal 9.

[0025] With reference to FIG. 3, cap 38 has been removed and the needleis now ready for use with the needle being shielded, but in fluidcommunication with the interior of the barrel 16 which accommodates themedicament.

[0026] Referring to FIG. 3A, the shield extender 14 has been rotated inthe reverse direction relative to the shield 12 such that the shieldextender 14 has moved forwardly relative to shield 12 from its fullyretracted position and it now extends forwardly beyond the forward-mostextent of shield 12. Selective rotation of shield extender 14 relativeto shield 12 allows the user to control the depth of penetration of theneedle 18 during use. The further the shield extender 14 is extendedbeyond the shield 12, the shallower the penetration of the needle 18 inthe patient.

[0027] With reference now to FIG. 4, the user has begun squeezingtogether thumb receiving portion 36 of the plunger assembly 20 andfinger-receiving portions 22 of the shield 12 in the conventional mannerthereby compressing compression spring 40 which is provided between asmall outwardly extending shoulder formed on the rear end of barrel 16and a small inwardly directed shoulder formed midway along the length ofshield 12.

[0028] As shown in FIG. 4, the plunger assembly 20 has not yet movedforwardly relative to barrel 16 to express medicament from the needle18. Rather, plunger assembly 20 and barrel 16 have moved forwardly inunison within shield 12 and shield extender 14. Plunger assembly 20 andbarrel 16 will continue to move forward in unison until the forward endof barrel 16 engages the forward end of shield 12 whereat thecompression spring 40 reaches its maximum compression.

[0029] With reference now to FIG. 5, the barrel 16 has moved to thefully forward position relative to shield 12 such that the forward endof barrel 16 engages the forward end of shield 12 and the needle 18 ismaximally exposed. Thereafter, any further squeezing together of thethumb receiving portion 36 and finger receiving portions 22 in theconventional manner causes the plunger assembly 20 to move forwardrelative to barrel 16 thereby expressing the medicament from theinterior of the barrel 16.

[0030] With reference to FIG. 5, it should be noted that the forward endof locking member 26 (which has been carried forward on the forward endof barrel 16) has engaged the circular slot 24 defined in the forwardend of shield 12. The locking member 26 is thereafter retained in thisposition by virtue of its engagement with the slot 24.

[0031] With reference to FIG. 6, the squeezing force applied by the userhas been discontinued and the barrel 16 and plunger assembly 20 havemoved rearwardly in unison under the influence of compression spring 20.It will be noted that locking member 26 is retained in the circular slot24 defined in the forward end of shield 12. As barrel 16 movesrearwardly relative to shield 12, locking member 26 slides or is pulledoff the forward end of barrel 16 until it is fully clear of barrel 16 asshown in FIG. 6. At this stage, the rear end of locking member 26, whichis formed of a resilient plastics material having a memory, snapsinwardly to adopt a truncated and bifurcated cone-like shape as shown inFIG. 6. Of course, previously whilst the locking member 26 wasencircling barrel 16, it adopted a bifurcated cylindrical shape. Thus,the resilient memory of the locking member 26 causes the locking memberto change shape from a generally cylindrical shape to a generallytruncated cone-like shape when it is “pulled” off the forward end of thebarrel 16 via its engagement with slot 24.

[0032] Once the locking member 26 has adopted the truncated cone-likeshape as shown in FIG. 6, subsequent forward movement of the barrel 16relative to the shield 12 is prevented by virtue of physicalinterference with the locking member 26 and hence the locking member 26prevents subsequent unshielding of the needle 18.

[0033] Referring to FIG. 7, the single-use syringe can also beconveniently used in a safe manner with intravenous polybags as shown.In this regard, the forward end of the shield 12 is sized so as toclosely receive the male port of a polybag as shown. Typically, thesemale ports are sealed by a rubber plug as shown. The needle canpenetrate through the rubber plug and the medicament can then beinjected into the polybag for IV feed to the patient via an establishedcatheter or the like. After injection of the medicament into thepolybag, the needle is withdrawn and the rubber plug is sufficientlyresilient to be reseal the male port of the poly bag.

[0034] The present invention provides a single-use syringe which issupplied to the user with the shield in the forward or shieldingposition, yet requires no non-conventional manipulation or activation ofrelease mechanisms or the like to move the shield back to theneedle-exposed position for use. Furthermore, no non-conventionalmanipulation of release mechanisms or the like is required to releasethe shield to the forward protective position after use. The user simplysqueezes their thumb and fingers together in the conventional manner andthis single, conventional action exposes the needle 18, activates thelocking member 26 via its engagement with the slot 24, and expresses themedicament. Discontinuation of the squeezing force cause the shield toreturn to its forward or protective position under spring bias whereatit is locked to prevent subsequent use or inadvertent needle-stickinjuries.

[0035] It will of course be realised that whilst the above has beengiven by way of an illustrative example of this invention, all such andother modifications and variations hereto, as would be apparent topersons skilled in the art, are deemed to fall within the broad scopeand ambit of this invention as is herein set forth.

What is claimed is:
 1. A single-use syringe, comprising: a shield; abarrel adapted to contain a medicament and mounted for axialreciprocation within the shield; and a locking member initially mountedon the barrel, wherein the locking member engages the shield duringexpression of medicament from the barrel, and subsequent to saidengagement is dismounted from the barrel, the dismounted locking memberthereafter preventing reciprocation of the barrel within the shield. 2.A single-use syringe as claimed in claim 1, wherein the locking memberinitially encircles a forward end of the barrel, and is dismounted fromthe forward end of the barrel during rearward reciprocation of thebarrel within the shield.
 3. A single-use syringe as claimed in claim 1,wherein the shield includes a slot, and wherein the locking memberengages, and is retained by, the slot.
 4. A single-use syringe,comprising: a shield; a barrel adapted to contain medicament and mountedfor axial reciprocation within the shield; and a locking memberinitially mounted relative to the barrel for reciprocation therewith,wherein the locking member engages and is retained by the shield duringexpression of medicament from the barrel, and as a result of saidengagement and retention the locking member is translated relative tothe barrel during rearward reciprocation of the barrel within theshield, the locking member then preventing subsequent reciprocation ofthe barrel within the shield.
 5. A single-use syringe comprising: ashield with a forward end and a rearward end; a barrel with a forwardend and a rearward end, the barrel mounted for axial reciprocationwithin the shield between a rearward position and a forward position; aneedle mounted on the forward end of the barrel such that when thebarrel is in the forward position the needle is exposed; a lockingmember adapted to prevent exposure of the needle by forwardreciprocation of the barrel when the locking member is dismounted fromthe barrel, the locking member being removably mounted to the forwardend of the barrel and adapted to engage the forward end of the shieldwhen the needle is exposed by forward reciprocation of the barrel, theengagement being sufficient to dismount the locking member from theforward end of the barrel during rearward reciprocation of the barrel,the locking member thereafter preventing further exposure of the needleby forward reciprocation of the barrel.